1. Field of the Invention
This invention lies in the field of seismographic vibrators for imparting to the earth a pulsating pressure of selected frequency and time duration.
2. Description of the Prior Art
In the prior art there are a number of patents covering designs of electro-hydraulic vibrators which vary over a very wide range of design and construction. Most of these vibrators have very intricate construction and have mechanical systems which are not simple and which at the various frequencies at which the vibrators are operated can provide considerable trouble with resonances and phase shifts.